Visual Basic Upgrade Companion vs. Code Advisor - ArtinSoft

More documents

Recommendations

Info

following objects are supported by VBUC by using helper classes implemented in .NET or by using special classes from the .NET Framework: • Printer Object • Printers Collection • Clipboard Object • Forms Collection Portions of code that use any other unsupported object will have to be rewritten in VB.NET. Declare with an early-bound data type Variables that were either not declared with a specific type or declared As Variant in VB6 are declared As Object in VB.NET. Since the actual type of a Variant (or late-bound) variable is not known until runtime, the Upgrade Wizard will not be able to determine which operations to apply to that variable, resulting in migration errors. For instance, since the type of the variable is not known at migration time, default properties will not be expanded, leading to issues and crashes when the migrated application is executed. The Visual Basic Upgrade Companion features an Artificial Intelligence-based type inference engine, which in most situations will be able to infer the type of a variable based on its usage in the source code, given that its runtime type remains consistent and that it interacts with literals and variables with known types. For example, the following code snippet Private Sub Sum() a = 1 b = 2 + 3 End Sub would be converted by VBUC to Private Sub Sum() Dim a As Byte = 1 Dim b As Byte = 2 + 3 End Sub Even when VBUC may not be able to infer the type of all the late-bound variables in the source code, it’s a good idea to let VBUC do as much work as it can do for you. Variables that still do not have a specific type after migration has taken place can be identified if you search for the following late binding Upgrade Warning 'UPGRADE_WARNING: Couldn't resolve default property of object . Replace function with function In Visual Basic 6.0, text functions such as Mid, Trim and Right have both a “String” version and a “Variant” version, where the first one returns a String type and the latter returns a Variant type. String versions of these functions are preferable since they avoid late binding. These strongly-typed functions can be recognized because their names end with a dollar sign (“$”), which is also used in
VB6 to denote string types. For instance, Mid has a Variant return type and Mid$ has a String return type. Many VB6 programmers were not aware of this difference and tended to use the Variant version of the function instead of the early-bound, String version. From a migration standpoint, using the Variant function increases the amount of late-bound variables, generates more Upgrade Warnings, and decreases the quality of the converted code. In the majority of cases, the Visual Basic Upgrade Companion will successfully infer the type of the variables and will automatically add a call to the appropriate function. For instance, the following Visual Basic 6.0 code fragment 'FIXIT: Declare 's' with an early-bound data type… Dim s s = "Hello World" 'FIXIT: Replace 'Mid' function with 'Mid$' function… s1 = Mid(s, 1, 4) 'FIXIT: Replace 'Right' function with 'Right$' function… s3 = Right(s, 4) 'FIXIT: Replace 'Trim' function with 'Trim$' function… s4 = Trim(s) 'FIXIT: Replace 'LTrim' function with 'LTrim$' function… s5 = LTrim(s) 'FIXIT: Replace 'RTrim' function with 'RTrim$' function… s6 = RTrim(s) would be converted to the following Visual Basic .NET code 'FIXIT: Declare 's' with an early-bound data type… Dim s As String = "Hello World" 'FIXIT: Replace 'Mid' function with 'Mid$' function… Dim s1 As String = s.Substring(0, 4) 'FIXIT: Replace 'Right' function with 'Right$' function… Dim s3 As String = s.Substring(s.Length - (Math.Min(s.Length, 4))) 'FIXIT: Replace 'Trim' function with 'Trim$' function… Dim s4 As String = s.Trim() 'FIXIT: Replace 'LTrim' function with 'LTrim$' function… Dim s5 As String = s.TrimStart() 'FIXIT: Replace 'RTrim' function with 'RTrim$' function… Dim s6 As String = s.TrimEnd() In this case, VBUC is able to infer the type of the variables, making the replacement of Variant functions with String functions unnecessary. Also, note how the conversion tool uses equivalent methods from the String class instead of backwards compatibility functions to perform the same operations. The use of is not valid for the property being assigned This FixIt usually appears when invalid enumeration values are being set for a property. In Visual Basic 6.0, you can assign invalid enumeration values to properties and still obtain the expected results if the underlying integer values are the same. For instance, “vbNormal” has been commonly used to set the MousePointer property of a window to its default, when the correct value is
Page 1: Visual Basic Upgrade Companion vs.
Page 5 and 6: forms or modules, and all the desig
Page 7 and 8: Table 3. FixIts generated on Applic
Page 9 and 10: [Click to Enlarge] Figure 5. Automa

Visual Basic Upgrade Companion vs. Code Advisor - ArtinSoft

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?